September 2024 | AIChE

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September 2024

Piping and Instrumentation Diagram (P&ID)

A diagram that shows the details about the piping, vessels, and instrumentation.

Pillar

See Accident prevention pillar.

Physical Models

Models that provide quantitative information on source rates and extent of damage (thermal radiation, explosion overpressure, or concentration of dispersing vapor clouds).

Physical Hazard

A chemical for which there is scientifically valid evidence that it is a combustible liquid, a compressed gas, explosive, flammable, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive) or water reactive.

Physical Explosion

The catastrophic rupture of a pressurized gas/vapor-filled vessel by means other than reaction, or the sudden phase-change from liquid to vapor of a superheated liquid.

Personal Protective Equipment (PPE)

Equipment designed to protect employees from serious workplace injuries or illnesses resulting from contact with chemical, radiological, physical, electrical, mechanical, or other workplace hazards. Besides face shields, safety glasses, hard hats, and safety shoes, PPE includes a variety of devices...

Permissive

An action required before a subsequent action can take place.

Permissible Exposure Limit (PEL)

The maximum permissible exposure limit for systemic workplace 8-hour time-weighted average exposures as established by OSHA

Permissible Exposure Limit (PEL)

An exposure established by OSHA regulatory authority. May be a Time Weighted Average (TWA) limit or a maximum concentration exposure limit. See also, "Skin". Importance: If a PEL is exceeded, a potential health hazard exists, and corrective action is necessary.

Permanent Building

Rigid structures intended for permanent use in fixed locations.

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